Please help me with some math!?

1) A hot air balloon is in the shape of a sphere. Approximately how much fabric was used to construct the balloon if its diameter is 38 feet? Use 3.14 for pi. round to the nearest hundred square feet.

You need to know two things:

(1) the radius of a sphere is half its diameter, and

(2) the surface area of a sphere is 4 * pi * the square of its radius.

Putting these together, we get a surface area of

4 * 3.14 * (38/2)^2

= 4 * 3.14 * 19^2

= 4,534.16 square feet.

To the nearest hundred square feet, that's

B) 4500 ft^2

2) How much glass is needed to make a fish tank that is 20 inches long, 12 inches wide, and 24 inches high? The fish tank is open at the top.

Measuring the perimeter around the base we get 64 inches, so the sides total 64*24 square inches and the bottom is 20*12 square inches.

That's 1536 + 240 = 1776 square inches, not one of the offered choices.

Assuming that the bottom isn't glass doesn't seem to fix the problem, since 1536 isn't an option either.

Are you sure you copied the measurements correctly?

3) You plan to stain the wooden deck attached to your house. The deck measures 15ft by 14 ft. A quart of stain will cost $9.70 and will cover 60ft^2. How many quarts of stain should you buy?

Notice we aren't asked to do anything using the cost of the stain.

The area of the deck is 14*15 = 210 square feet, and that requires

210/60 = 3.5 quarts of stain, so buy

C) 4 qt